The present embodiments relate to a contour collimator and an associated method for radiation therapy.
A contour collimator is used in radiation therapy to treat tumors. In radiation therapy, a tumor is irradiated with energy-rich radiation (e.g., using high-energy x-rays from a linear accelerator). In the process, the contour collimator is introduced into the radiation path of the x-rays. The contour collimator has a radiation-permeable opening, the contour of which is to correspond to the contour of the tumor. The contour therefore forms an aperture to allow the x-rays to pass. Only the tumor and not the surrounding healthy body tissue is irradiated with x-rays. The contour collimator allows almost any arbitrary contour of a tumor to be reproduced.
Many collimators for radiation therapy are multi-leaf collimators such as are described, for example, in the application DE 10 2006 039793 B3. The multi-leaf collimator includes a number of leaves (e.g., 160 leaves) that may be moved in a motor-driven manner counter to one another in order to form the opening. The leaves include a material absorbing the x-ray radiation. In generic terms, two leaf packages are arranged opposite one another such that the two leaf packages may be moved with front faces towards or away from one another.
Each of the leaves may be moved separately by an electric motor. Since during the positioning of the leaves slight deviations may occur between a target specification and the actual position of the leaves set, each leaf has a position measuring device, with which the actually set position may be determined precisely.
The unexamined patent application US 2009/0 010 395 A1 discloses a contour collimator having a liquid impermeable to x-rays that is arranged in a container. The shape of the contour forms a contour bounding the radiation path.
The patents U.S. Pat. No. 6,188,749 B1 and U.S. Pat. No. 6,118,855 A disclose contour collimators with liquids.